Sealing mechanisms for floating roofs for storage tanks



J. .H. WIGGINS 3,119,510 SEALING MECHANISMS FOR FLOATING ROOFS FOR STORAGE TANKS Jan. 28, 1964 4 Sheets-Sheet 1 Filed Nov. 21, 1960 IN V E N T08. tfo/m H W/gg/m J. H. WIGGINS 3,119,510 SEALING MECHANISMS FOR FLOATING ROOFS FOR STORAGE TANKS Jan. 28, 1964 4 Sheets-Sheet 2 Filed Nov. 21. 1960 IN V EN TOR. /0/10 H VV/gg/hs Jan. 28, 1964 J- H. WIGGINS SEALING MECHANISMS FOR FLOATING ROOFS FOR STORAGE TANKS 4 Sheets-Sheet 3 Filed Nov. 21, 1960 VIIIIIIII/ III IIIIIIHII;;;;IIII

I N V EN TOR. JO/m H 1449 1275 J. H. WIGGINS Jan. 28, 1964 SEALING MECHANISMS FOR FLOATING ROOFS FOR STORAGE TANKS 4 Sheets-Sheet 4 Filed Nov. 21, 1960 uoum LEVEL IN V EN TOR. John H l V/gg/ns United States Patent F 3,11%,518 SEALING IidEQHANiSIt ES FGR FLQATENG RQQFS John H Wiggins, dill C El Camino Real, Menlo hark, Calif. Filed Nov. 21, 193i), Ser. No. 76,487 16 Claims. (ill. Mil-26} The present invention relates to sealing mechanisms for floating roofs provided in storage tanks for petroleum products, or the like, and more particularly to such a storage tank of the type having an upstanding substantially cylindrical side wall and provided with a floating roof carrying both sealing mechanism for minimizing the evaporation of the stored petroleum products and weather hood mechanism for protecting the sealing mechanism from the elements of the weather.

It is a general object of the invention to provide sealing mechanism of the type noted that is of improved and simplified construction and arrangement.

Another object of the invention is to provide in a storage tank of the type noted, improved sealing mechanism that is in constant and adequate contact with the inner surface of the side wall of Le storage tank, notwithstanding substantial irregularities in the contour of the side wall.

Another object of the invention is to provide in a storage tank incorporating a floating roof and carrying sealing mechanism in the annular space between the side wall of the storage tank and the annular outer structure of the floating roof, the combination of weather hood mechanism also carried by the floating roof and positioned over the sealing mechanism in order to protect the same against the elements of the weather.

Another object of the invention is to provide a sealing mechanism of the type noted, incorporating a substantially annular sealing shoe arranged in the substantially annular space disposed between the substantially cylindrical tank side wall and the substantially cylindrical wall structure of the floating roof and disposed in sliding sealed engagement with the tank side wall, wherein the sealing shoe is of composite construction including an outer sealing layer of elastomeric material that is highly impervious to the constituents of petroleum products and disposed directly in sliding sealed engagement with the adjacent inner surface of the tank side wall, and an adjacent resilient cushioning layer bacldng up the outer sealing layer mentioned and pressing the same into firm sealed engagement with the tank side wall, and an adjacent resilient backing member disposed in contact with the cushioning layer mentioned and resiliently urging the same radially outwardly into cushioning relationship with respect to the outer sealing layer mentioned.

Another object of the invention is to provide a composite sealing shoe of the character described, wherein the three major individual components thereof noted are each formed of improved constructional materials.

Another object of the invention is to provide a sealing mechanism of the type noted, incorporating a substantially annular sealing element arranged in the substantially annular space disposed between the substantially cylindrical tank side wall and the substantially cylindrical wall structure of the floating roof and disposed in sliding sealed engagement with the tank side wall, and a plurality of circumferentially spaced-apart pusher devices of improved construction and arrangement and resiliently urging the sealing element into firm sealed engagement with the adjacent tank side wall.

A further object of the invention is to provide a sealing mechanism of the character described, incorporating both a substantially annular sealing element disposed adjacent to the tank side wall and a substantially annular flexible Patented Jan. 28, 1%4

diaphragm sealed to the substantially cylindrical wall structure of the floating roof, wherein the sealing element is of composite construction including an outer sealing layer that is disposed in sliding sealed engagement with the tank side wall and that comprises a continuation of the flexible diaphragm mentioned and formed of the same body of flexible sheet-like material therewith.

A still further object of the invention is to provide a sealing mechanism of the type mentioned, wherein at least a portion of the sealing element and the whole of the sealing diaphragm extending between the sealing element and the substantially cylindrical wall structure of the floating roof comprise a continuous integral layer of flexible sheet-like material that is highly resistant to the constituents of petroleum products.

Further features of the nivention pertain to the particular arrangement of the elements of the sealing mechanism, whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a fragmentary plan view, partly broken away, of a tank for storing liquids, such as petroleum products, and provided with a floating roof carrying sealing mechanism embodying the present invention;

FIG. 2 is an enlarged fragmentary vertical sectional view, taken through the side wall of the tank and the outer annular pontoon of the floating roof and the sealing mechanism carried by the outer pontoon and arranged in the annular space between the tank side wall and the outer pontoon, this view being taken in the direction of the arrows along the line 2-2 in FIG. 1;

FIG. 3 is an enlarged fragmentary vertical sectional view, similar to FIG. 2, this View being taken in the direction of the arrows along the line 33 in FIG. 1;

FIG. 4 is a greatly enlarged fragmentary front elevational view of one of the joints between the overlapped ends of two of the arcuate segments of the composite sealing shoe, this view being taken in the direction of the arrows along the line 44 in FIG. 1;

FIG. 5 is a greatly enlarged fragmentary vertical sectional view, similar to FIG. 2, of the extreme lower portion of the sealing shoe, illustrating the junction between the lower peripheral portion and the outer peripheral portion of the respective sealing section and diaphragm section of the flexible sheet-like element that is incorporating in the sealing mechanism;

FIG. 6 is a greatly enlarged fragmentary rear view of a modified form of the sealing shoe and the sealing section of the flexible sheet-like element that may be incorporated in the sealing mechanism;

'FIG. 7 is a greatly enlarged fragmentary vertical sectional view of the modified form of the sealing shoe and the sealing section of the flexible sheet-like element that is incorporated in the sealing mechanism, this view being taken in the direction of the arrows along the line 7-7 in H6. 6;

PEG. 8 is a greatly enlarged fragmentary vertical sectional view of another modified form of the sealing shoe and the sealing section of the flexible sheet-like element that may be incorporated in the sealing mechanism; and

FIG. 9 is a greatly enlarged fragmentary vertical section-a1 view of a further modified form of the composite sealing element that may be incorporated in the sealing mechanism.

Referring now to FIGS. 1 to 3, inclusive, of the dravings, there is illustrated a tank it) for storing liquids, such as petroleum products, indicated at 11, that includes an upstandin substantially cylindrical side Wall 12 and provided w-.1h an open top, and containing a substantially annular floating roof arranged in floating relation with respect to the liquid 11 stored in the tank 1%; whereby the heating roof 2% rises and falls with respect to the side Wall 12 of the tank 10 in accordance with the head of the body of liquid 11 stored therein, the level of the body or" liquid 11 stored in the tank iii being indicated at 13 in FIG. 2.

The floating roof 29 comprises an outer annular structure defining an outer annular pontoon 2 1, inner annular structure defining a centrally disposed annular pontoon, not shown, and connecting annular structure defining a deck 22 disposed between the outer pontoon 21 and the inner pontoon, not shown. The outer pontoon 21 comprises an upstanding substantially cylindrical wall or rim structure 24- spaced radially inwardly from the tank side wall 12 and defining an annular space 25 therebetween; and arranged Within the annular space 25 and carried by the floating roof 2t} is sealing mechanism embodying the features of the present invention. As indicated in EEG. 2, when the roof 2%} is floating upon the body of liquid -11 stored in the tank it), the bottom of the outer pontoon 21 is submerged therein and the liquid 11 is in contact with the lower surface of the deck 22, the level of the liquid 11 being indicated by the broken line 13, as previously noted.

Continuing the reference to FIGS. 1 to 3, inclusive, the sealing mechanism 3%} for the annular space 25 comprises an upstanding substantially annular sealing element or shoe 4t? of composite construction, described more fully hereinafter; which shoe is disposed closely adjacent to the inner surface of the tank side Wall 12, and is carried by the upstanding wall structure or rim 2d of the outer pontoon Ed. in the arrangement, the top of the shoe 40 projects upwardly above the top of the outer pontoon 21, while the bottom of the shoe 40 projects downwardly below the level of the body of liquid 11 stored in the tank it as clearly shown in FIG. 2. More particularly, the composite shoe t comprises a plurality of arcu-ate segments 4-1 arranged in overlapped end relation, as illustrated in FIG. "1, each of the segments 41 being formed of limber sheet material.

Referring now to FIGS. 1 and 4, the overlapped ends of the adjacent arcuate segments 41 of the composite shoe td are secured together by a composite clamping device 50, including complementary clamping elements 51 and 52 respectively secured to the inner and outer segments 41 adjacent to the overlapped joint between the respective edges thereof. Specifically, the clamping element 51 is suitably secured to the inner segment 41 by a pair of bolts 53, and the clamping element 52 is suitably securcd to the outer segment 41 by a pair of bolts 54. The clamping element 51 is provided with a pair of spaced-apart arms 55 projecting circumferentially toward the left there rom, while the clamping el ment 52 is provided with a single arm 5'6 projecting circumferentially toward the right therefrom, the extreme outer end of the arm 56 being positioned between the extreme outer ends of the arms 55, and the adjacent ends of the arms 55 and 55 being suitably secured together by a cooperating bolt 57 projecting through aligned holes provided therein and carrying a nut in the arrangement, the holes provided in the extreme outer ends of the arms 55 and 55 accommodate slight circumferential movements of the clamping elements 51 and 52 with respect to each other as the arcuate segments 41 of the composite shoe 4% are expanded and contracted circumferential-l as required, for the purpose of maintaining the composite shoe 4% pressed radially outwardly from the outer pontoon 21 toward the tank side wall 12, as explained more fully hereinafter.

The upstanding substantially cylindrical composite annular shoe 3?} is carried by and mounted upon the upstanding substantially cylindrical Wall structure or rim 2d of the outer pontoon 21 by an arrangement comprising a plurality of pusher devices 69 and a plurality of hanger devices 78*, all arranged in the annular space 25 and disposed in circum erentially spaced-apart relation, a shown in FIG. ll. More specifically, wo zuigularly displaced pusher devices 6% may be disposed between each adjacent pair of angularly displaced hanger devices and two pusher devices 6t; and one hanger device 7% may be conveniently provided for each arcuate segment 41 of the composite shoe 4%.

As illustrated in PlGS. l, 2 and 3, the angularly spacedapart pusher devices so may be disposed in a substantially horizontfl intermediate plane passing through the upper central portion of the outer pontoon 21, while the angularly spaced-apart hanger devices 7t may be disposed in a substantially horizontal upper plane passing through the upper portion of the outer pontoon 21; whereby the plane or" the pusher devices as is disposed below the plane of the hanger devices ill; and both the pusher devices 69 and the hanger devices 7% are disposed entirely within the annular space 25 and below the top of the substantially annular wall structure or rim 2 5 of the outer pontoon 21.

Again referring to FIGS. 1 and 2, the composite shoe 4% comprises a radially yieldable backing member, as explained more fully hereinafter, that is formed of limber sheet material, as previously noted. More particularly, each of the arcuate segments of the composite shoe 40 may be formed of mold steel that has been given a suit able weather-resistant coating, such as a galvanized coating. Alternatively, each of the arcuate sections 41 may be formed of plastic sheet material, such, for example, as a synthetic organic plastic resin consisting essentially of polyesters reinforced with glass fibers. In any case, each of the arcuate segments 41 is sufliciently limber and flexible so that it is radially yieldable for a purpose more fully explained hereinafter.

Continuing the reference to FIGS. 1 and 2, each of the pusher devices 64? essentially comprises a block of cellular material characterized by resiliency so that when it is deformed from its normal configuration by compressive forces, it reacts with similar expansive forces tending to return into its normal configuration. More particularly, this block is formed of synthetic organic resin, and is preferably formed of foamed polyurethane resin; whereby the same is also highly resistant to the deleterious efiects of the constituents of petroleum products. This foamed synthetic resin is of the open-cell type and highly resilient. Moreover, each of the pusher devices 60 is arranged in compression between the outer surface of the substantially cylindrical wall structure or rim 24 of the outer pontoon 21 and the adjacent inner surface of the associated arouate segment 41 of the composite sealing shoe 453. In the arrangement, the inner end of the pusher device 69 may be vulcanized or cemented or otherwise secured to the adjacent outer surface of the wall structure or rim 24, as indicated at 61 in FIG. 2; and the outer end of the pusher device 60 may be vulcanized or cemented or otherwise secured to the adjacent inner or rear surface of the associated arcuate segment &1, as indicated at 62 in FIG. 2.

Again referring to FIGS. 1 and 3, each of the hanger devices 79 essentially comprises a link construction including an inner bracket 71 rigidly secured to the adjacent outer surface of the wall structure or rim 24 of the outer pontoon 21 and an outer bracket '72 rigidly secured to the adjacent inner surface of the adjacent arcuate segment 4-1 of the composite shoe 46, as well as four arms or links 73, '74, 75 and 76. In the arrangement, the inner end of the link 73 is pivotally connected by an associated pintle to the inner bracket 71, the outer end of the link '74 is pivotally connected by an associated pintle to the outer bracket 72, and the adjacent ends of the links 73 and 74 are pivotally connected together by an associated pintlc. Similarly, the inner end of the link 75 is pivotally connected by an associated pintle to the inner bracket '71, the outer end of the link 76 is pivotally connected by an associated pintle to the outer bracket 72, and the adjacent ends of the links 75 and 76 are pivotally connected together by an associated pintle. Accordingly, the hanger device 70 constitutes a relatively rigid cantilever construction for supporting the sealing shoe 40 upon the wall structure 24 of the outer pontoon 21, and the cantilever construction is collapsible horizontally to accommodate relative radial movements and rotational movements of the outer pontoon 21 with respect to the sealing shoe 4% More particularly, in the sealing mechanism 38, the sealing shoe 4% is supported from the outer pontoon 21 in the annular space 125 and closely adjacent to the inner surface of the tank side wall 12 fundamentally by the annular series of hanger devices 769, and the sealing shoe 4%) is urged radially outwardly toward the tank side wall 12 fundamentally by the resiliency of the pusher devices 64). This mounting arrangement insures that there is minimum vertical displacement or relative movements between the sealing shoe 4% and the outer pontoon 21 as the floating roof 2t) rises and falls in the tank with the head of the body 11 of stored petroleum products contained therein. Furthermore, this mounting arrangement accommodates limited radial movements of the floating roof with respect to the tank 10 while maintaining the sealing shoe 4t} pressed radially outwardly toward the inner surface of the tank side wall 12.

Again referring to FIGS. 1 and 2, the sealing mechanism 39 further comprises a substantially annular element 80 arranged in the annular space and formed of flexible sheet material that is highly resistant to the constituents of petroleum products, the element 80 including an outer wear-resistant sealing section 81 and an inner gas-impervious diaphragm section 82. More particularly, the complementary sections 81 and 82 of the annular element 84 are formed integrally with each other of a single piece or run of the flexible sheet material that may comprise a suitable rubberized fabric, or the like. Specifically, the sealing section 8'1 is disposed between the tank side wall 12 and the sealing shoe 4%, and the diaphragm section 82 extends between the wall structure or rim 24 of the outer pontoon 21 and the bottom of the sealing shoe 40. The upper peripheral portion of the sealing section 81 is attached to an annular portion of the sealing shoe 4t? disposed above the level of the liquid 11 stored in the tank It and the lower peripheral portion of the sealing section 81 is attached to an annular portion of the sealing shoe disposed below the level of the liquid ll stored in the tank 19. More particularly, the extreme upper edge portion 810 of the sealing section 81 is folded over the extreme top edge of the sealing shoe 4t} and thence downwardly over the inner surface thereof and secured in place by a plurality of circumferentially spaced-apart clamping fixtures 99* that, in turn, are suitably secured to the top of the sealing shoe 4%). Specifically, a lurality of the circumferentially spacedapart fixture 9d are carried by the top of each of the arouate segments =41, as best shown in FIG. 1.

Referring now to FIGS. 2 and 5, the lower peripheral portion of the sealing section 81 joins the outer periph eral portion of the diaphragm section 82 adjacent to the bottom of the sealing shoe it and below the level of the liquid ll stored in the tank It and submerged therein; and specifically, the junction between the two sections 81 and 82 is arranged immediately below the bottom edge of the sealing shoe 40 and attached thereto by a plurality of circumferentially spaced-apart pull-down tabs 95 carried by each of the arcuate segments 41. As best shown in FIG. 5, each of the tabs 95 may be formed of sheet metal and is affixed to the extreme bottom edge of the adjacent arcuate segment 41; and, in turn, the junction between the sections 81 and 82 of the element 80 wraps around the tab 95 and is secured in place by an intervening layer of adhesive, or cement, as indicated at 96 in FIG. 5.

Accordingly, it will be understood that the upper peripheral portion of the sealing section 81 is securely attached to the top of the sealing shoe 40 by the arrangement including the plurality of circumferentially spacedapart fixtures ha), and the lower peripheral portion of the sealing section 81 is securely attached to the bottom of the sealing shoe it by the arrangement including the plurality of circumferentially spaced-apart tabs and further, it will be appreciated that the sealing section 81 is pressed radially outwardly by the sealing shoe 40 into firm sliding sealed engagement with the inner surface of the tank side wall 12. In turn, the sealing shoe 4%) is pressed radially outwardly toward the tank side wall 12 fundamentally by the plurality of circumferentially spaced-apart pusher devices 6% as previously explained. In the arrangement, the sealing section 81 covers the outer surface of the sealing shoe 40 and is maintained in a substantially flat condition, as the sealing shoe 40 rises and falls with the floating roof 20 and with respect to the tank side wall 12 by virtue of the attachments of the upper and lower peripheral portions of the sealing section 81 respectively to the top and to the bottom of the sealing shoe all, as previously explained. Furthermore, the sealing section 81 is maintained in compression between the sealing shoe 4%) and the tank side wall 12 and possesses sufficient resiliency so as to maintain an hermetic seal with respect to the tank side wall 12, notwithstanding substantial irregularities in the surface thereof.

Finally, the inner peripheral portion of the diaphragm section 82 is sealed to an'annular portion of the wall structure or rim 24 disposed above the level of the liquid 11 stored in the tank lit) by an annular sealing bar 97. More particularly, the sealing bar 97 is carried by the wall structure or rim 24 and receives the inner peripheral portion of the diaphragm section 82 therein, clamping the same in place in hermetically sealed relation to the wall structure or rim 24-.

Again referring to FIG. 2, it will be observed that the diaphragm section 82 comprises an inner part 82a, an outer part 82b and an intermediate part 820. The intermediate part 32c lies along the level 13 of the liquid ll stored in the tank W and extends between the bottom of the inner part 32a and the top of the outer part 32b. The inner part 32a is disposed above the liquid level 13 and lies along the outer surface of the wall structure or rim 24 of the outer pontoon 21 extending upwardly therealong to the sealing bar 97; and the outer part 82b is disposed below the liquid level 13 and submerged in the liquid 11 and lies along the lower inner surface of the sealing shoe til extending downwardly to the junction between the sealing section 551 and the die: phragm section 82, that is disposed below the bottom of the sealing shoe ii The diaphragm section 32 is loosely draped between the sealing bar 97 and the bottom of the sealing shoe 4% with the result that the intermediate part 826 thereof contains substantial wrinkles or folds in the extension thereof between the inner part 82a and the outer part @Zb; whereby the radial length of the diaphragm section 32 between the sealing bar 97 and the bottom of the sealing shoe 4%) is substantially greater than the radial width of the annular space 25 between the wall structure or rim 24 of the outer pontoon 21 and the sealing shoe 49, even when the annular space 25 has a maximum radial width as a consequence of sidewise movement of the floating roof 24) away from the adjacent portion of the tank side wall 12.

Considering now the draft of the outer pontoon 21 in the liquid 11 stored in the tank It when the floating roof 2%) is unburdened with snow, rain, or the like, the submergence thereof may be relatively small, as indicated by the liquid level 13, as shown in FIG. 2; whereby the flexible material in the outer part 82b of the diaphragm section $2 is fed or payed-out into the intermediate part 820 thereof and thence into the inner part 82a thereof. On the other hand, when the floating roof 20 is heavily burdened, the submergence thereof may be relatively great, as indicated by the broken liquid level line 13, as shown in FIG. 2; whereby the flexible material in the inner part 82a of the diaphragm section 82 is fed or payedout into the intermediate part 820 thereof and thence into the outer part 82b thereof. Of course, the sealing shoe 4% follows the draft of the floating roof 29 either increasing or decreasing the submergence of the bottom thereof as the draft of the outer pontoon 2-1 is correspondingly increased or decreased in the liquid ill contained in the tank 19. Further, it will be understood that the hydrostatic pressure of the liquid 11 maintains the submerged outer part 82b of the diaphragm section 82 pressed into firm engagement with the lower inner surface of the sealing shoe 40, while gravity maintains the inner part 82a of the diaphragm section $2. disposed above the liquid level 13 in position in engagement with the outer surface of the wall structure or rim 24 of the outer pontoon 21, notwithstanding variation in the draft of the outer ponteen 21 in the liquid 11 contained in the tank H9.

Further, the sealing mechanism 35 comprises an upstanding vent pipe 98 that is carried by the outer pontoon 2 1 and communicates at the lower end thereof with the lower portion of the annular space 25 disposed below the diaphragm section 82 and communicates at the upper end thereof with the atmosphere. More particularly, the vent pipe 93 has a substantially L-shape, the lower end of the vent pipe 93 being sealed into a cooperating opening provided in the wall structure or 24 of the outer pontoon 2 1 at a position disposed immediately below the sealing bar N, so that the extreme lower end of the vent pipe 98 is normally closed by the overlying inner part 32a of the diaphragm section 82. The upper end of the vent pipe 98 is sealed into a cooperating opening, not shown, provided in the top of the outer pontoon 2i and communicates somewhat th-ereabove with the atmosphere, as previously noted. It will be understood that in the event of an abnormal accumulation of gaseous products below the diaphragm section $2 and above the liquid level 13, the intermediate part 820 of the diaphragm section 82 will be blown upwardly causing the inner part 82a thereof to uncover the extreme lower end of the vent pipe 98, so that the gaseous products mentioned may escape from below the diaphragm section 82 through the vent pipe 98 to the atmosphere above the top of the outer pontoon 2.1.

Finally, the floating roof 2d is provided with a weather hood mechanism ith) that includes a plurality of segmental plates 1%]. disposed in an arcuate array in overlapping relationship adjacent to the ends thereof, :as indicated in FIG. 1. More particularly, the annular series of fixtures 99 that are carried by the sealing shoe 49 adjacent to the top inner surface thereof are employed for the purpose of detachably sectring in place the segmental plates iti'l. Specifically, the fixtures 9t carry a corresponding plurality of removable pins 1&2 that project through corresponding openings provided through the outer edges of the segment plates .18 1. The plates 131 are inclined downwardly from the outer peripheral portions thereof over the top of the annular space 25, so that the inner peripheral edges thereof are disposed in overhanging relation with respect to the top of the outer pontoon 2d, the inner portions of the plates 152i. being supported by an annular series of posts 193 carried by the top of the outer pontoon 21 adjacent to the wall structure or rim 24- thereof, as clearly shown in HG. 2. Accordingly, the plates ltld being detachably secured to the fixtures 99 carried by the top of the sealing shoe 4% accommodate relative radial movements and rotational movements of the outer pontoon 21 with respect to the sealing shoe ill with the sealing section 81 of the element 8t; disposed in sliding sealed engagement with the adjacent inner surface of the tank side Wall 12. Of course, the weather hood mechanism 1% serves the function of preventing the entry of rain water and other elements of the weather into the annular space 25, thereby to protect the pusher 8 devices 6%, the hanger devices 70, the sealing shoe 40 and the diaphragm section 82 of the element 8@ against damage by contact thereof with the elements of the weather.

As previously explained, the composite element St), including the sealing section lid and the diaphragm section 82, may be formed of a suitable continuous run of rubberized fabric; however, the element 85) may be advantageously donned of a sheet of synthetic onganic resinous material. Specifically, the sheet material of rubberlzike composition that is sold commercially under the name Ensolite Type M by the U. S. Rubber Company may be employed. Specifically, this material is of synthetic rubber-like composition comprising nitrile nuhber modified by polyvinyl chloride resin, the composition containing by weight about of the nitrile nibber, in turn, the nitrile rubber comprises copolymers of butadiene and acrylonitnile, the butadiene content ranging from about 55% to by weight. This synthetic nubber composition is of the closed-cell type and is of a tough cellular construction, having the general appearance of foamed rubber. Moreover, the composition is capable of vulcanization in :a manner entirely similar to that of natural rubber, but exhibits superior resistance to oils and solvents in general, and withstands the eifect of aging, abrasion and heat much better than natural rubber. Also, this synthetic rubber composition is superior to natural rubber with respect to minimizing swelling thereof the presence of petroleum products and is, or course, highly impervious to the constituents of such petroleum products.

In view of the foregoing, it will be understood that the element 3% hermetically seals the Wall structure or him 24: of the outer pontoon 2 1 to the tank side wall 12 by virtue of the fact that the inner peripheral portion of the diaphragm section 82 is hermetically sealed to the Wall structure or rim 2d at the sealing bar 97, and the fact that the sealing section 81 of the element 8% is pressed into firm sliding sealed engagement by the sealing shoe 49 with the inner surface of the tank side wall 12, and nothwithstandin g substantial irregularities in the inner surface of the tank side Wall 12. The hermetic seal mentioned is continuous by virtue of the integral construction of the sealing section 81 and the diaphragm section 82 0f the element 34' and notwithstanding the fact that the arcuate segments 41 of the sealing shoe 40 are not hermetically sealed to each other at the overlapped joints therebetween.

Referring now to FIGS. 6 and 7, a modified form of the sealing mechanism is there illustrated in cooperating relation with the tank side wall 12 and that is employed for the previously explained purpose of providing an hermetic seal between the wall structure or rim 24 of the outer pontoon 21 and the tank side wall 12. In this construction, the sealing mechanism 13% comprising the upstanding substantially annular sealing shoe 114i) and the substantially annular element 18% formed of flexible sheet material and including the sealing section 181 and the diaphragm section 1552. Again, the sealing shoe 14% is of composite construction, including the plurality of arcuate segments 141, as previously described. The upper portion Edda of the sealing shoe 14A) is disposed closely adjacent to the tank side wall 12 with the sealing section 1551 of the element 130 theriebetween, while the lower portion b :of the sealing shoe 14h is disposed in inwardly offset relation with respect to the upper portion 149a thereof and with the sealing section 181 of the element 1 8d disposed outwardly therefrom and in engagement with the tank side wall 12; whereby an annular space M2 is provided between the lower portion Idlib of the sealirrg shoe 14d and the adjacent portion of the sealing section 18 1 of the element 181). Further, an annular cushioning layer 143 is arranged in the lower portion of the annular space 142 and between the lower portion 14% of the sealing shoe 4% and the lower portion of the adjacent sealing section 181 of the element which cushioning layer 143 is provided for the purpose of distributing the radially outward pressure of the sealing shoe 1% upon the sealing section 1 81 so as to insure that the sealing section 131 is pressed into firm sliding sealed engagement with the inner surface of the tank side wall 12.

In this construction, a plurality of circumferentially spacedapart radially inwardly directed bosses 14% are provided adjacent to the top of the upper portion 14th: of the sealing shoe 1%; and a plurality of radially spacedapart clamping fixtures 1% are respectively carried by the bosses 1490, each of the clamping fixtures 190* being secured in place by an associated cooperating screw 191 provided with an associated nut 192. More particularly, the extreme upper peripheral portion of the sealing section 185 is wrapped over the extreme top edge of the upper portion 14% of the sealing shoe 140' and thence downwardly along the inner surface thereof and between the top of the upper portion 143a of the sealing shoe 14 and the associated clamping fixture 190, as clearly shown in FIG. 7. In the arrangement, the shank of the screw 1% extends through aligned openings provided in the sealing section 131, in the boss 14% and in the clamping fixture 19%, thereby to retain these parts together and securely to affix the upper peripheral portion of the sealing section 181 to the top of the upper portion 1400 of the sealing shoe 14 6'. Moreover, the head of the screw 191 is disposed in the concavity of the boss 14th: so that it is out of sliding engagement with the adjacent inner surface of the tank side wall 12.

The lower peripheral portion of the sealing section 18-1 and the outer peripheral portion of the diaphragm sec tion 132 are securely afiixed to the bottom of the lower portion 14% of the sealing shoe ldll by an arrangement including a plurality of circumferentially spaced-apart tabs 195 carried by the bottom of the lower portion 14% of the sealing shoe 141). More particularly, the extreme bottom end of 113 lower portion 14% is bent upwardly to provide a ledge 14nd that carries each of the tabs 195, as clearly shown in FIGS. 6 and 7. In turn, each of the tabs 1% is secured in place by an associated wedge 196 that is driven in place between the tab 1% and the adjacent lower portion 14% of the sealing shoe 1%. Finally, the tab 1% is afiixed to the adjacent lower peripheral portion of the sealing section 181 and to the adjacent outer peripheral portion of the diaphragm section 182 at the junction therebetween by an intervening layer of cement, indicated at 1950 in FIG. 7.

Accordingly, it will be tmderstood that in this modified form of the sealing mechanism 138' of FIGS. 6 and 7, the upper peripheral portion of the sealing section 181 is attached to the top of the upper po-riton 141301 of the sealing shoe 1 by the arrangement including the plurality of clamping fixtures 19:) and the cooperating plurality of screws 1%1, while the lower peripheral portion of the sealing section 181 is attached to the bottom of the lower portion 14% of the sealing shoe 1 th by the arrangement including the plurality of tabs 195 and the cooperating plurality of wedges 19-6. Also, the cushioning layer 1143 serves to distribute the radially outwardly directed pressure of the lower portion 1 59b of the sealing shoe 14a to the adjacent lower portion of the sealing section 131, thereby to insure that the sealing section 181 is in firm sliding sealed engagement with the inner surface of the tank side wall 12.

In this form of the sealing mechanism 135 the materials of construction of the sealing shoe 1% and of the element 180 may correspond to those previously described in conjunction with the sealing shoe all and the element 80, while the cushioning layer 143 may be formed of a suitable cellular rubber-like material, such, for example, as foamed polyurethane. The general mode of operation of the sealing mechanism 130 is the same as that of the sealing mechanism 3%, as previously described, and is not reiterated in the interest of brevity.

Referring now to FIG. 8, another modified form of the sealing mechanism 231 is there illustrated in cooperating relation with the tank side wall 12 and that is employed for the previously explained purpose of providing an hermetic seal between the wall structure or rim 24 of the outer pontoon 21 and the tank side wall 12. In this construction, the sealing mechanism 236 comprises the upstanding substantially annular sea-ling shoe 2% and the substantially annular element 23tlfo1med of flexible sheet material and including the sealing section 281 and the diaphragm section 282. Again, the sealing shoe 249* is of composite construction including the plurality of arcnate segments 241, as previously explained.

In this construction, the upper peripheral portion of the sealing section 2%1 of the element 28% is provided with a relatively thick cushion part 231A that is secured and sealed to the adjacent upper outer surface of the sealing shoe 24s by an intervening layer of cement, as indicated at 245; and similarly, the lower peripheral portion of the sealing section 231 or" the element 281 is provided with a relatively thick cushion part 2313 that is secured and sealed to the adjacent lower outer surface of the sealing shoe 24d by an intervening layer of cement, as indicated at 2 46. Likewise, the outer peripheral portion of the diaphragm section 282 of the element 2 3% is secured and sealed to the adjacent lower inner surtace of the sealing shoe 249 by an intervening layer of cement, as indicated at 247. Also, in this construction, the intermediate part 231C of the sealing section 231 is disposed radially outwardly from the sealing shoe 2% to provide an annular lElIl' space 242' therebetween.

In this construction, the cushion parts 21A and 2813 of the sealing section 281 insure the distribution of the radially outward pressing forces of the sealing shoe 24% upon the inner surface of the tank side wall 12 so as to insure that the sealing section 231 is in firm sliding sealed engagement with the inner surface of the tank side wall 12, for the purpose previously explained.

In this form of the sealing mechanism 230, the materials of construction of the sealing shoe 244} and of the element 281} may correspond to those previously described in conjunction with the sealing shoe 4t and the element 80. The general mode of operation of the sealing mechanism 230 is the same as that of the sealing mechanism 3! as previously described, and is not reiterated in the interest of brevity.

Referring now to FIG. 9, a further modified form of the sealing mechanism see is there illustrated in cooperating relation with the tank side wall 12 and that is employed for the previously explained purpose of providing an hermetic seal between the wall structure or rim 24 of the outer pontoon 21 and the tank side wall 12;. In this construction, the sealing mechanism 336) comprises the upstanding substantially annular sealing shoe sac and the substantially annular element 389 formed of flexible sheet material and including the sealing section 381 and the diaphragm section 382. Again, the sealing shoe 34% is of composite construction including the plurality of arcuate segments 341, as previously described.

In this construction, the top peripheral portion of the sealing shoe 340 extends radially inwardly, as indicated at 342, and carries a substantially annular rim guard 343 that is securely afiixed and sealed thereto by an associated layer of cement, as indicated at 344; and likewise, the lower peripheral portion of the sealing shoe 341) extends radially inwardly, as indicated at 345, and carries a substantially annular rim guard 346 that is securely afiixed and sealed thereto by an associated layer of cement, as indicated at 347. More particularly, the rim guards 343 and 346 are formed of resilient rubber-like material, such, for example, as foamed polyurethane; and the rim guards 343 and 346 are provided with elongated slots therein that respectively receive the top peripheral portion 342 and the bottom peripheral portion 345 of the sealing shoe 34% In this construction, a cushioning layer 348 is arranged 1 1 between the outer surface of the sealing shoe 34% and the inner surface of the sealing section 331 of the element 33%, which cushioning layer 343 is of resilient cellular structure, and may be formed of foamed polyurethane.

In the arrangement, the upper peripheral portion of the sealing section 331 is wrapped around the upper rim guard 343 and is aiflxed and sealed thereto by an intervening layer of cement 343', and likewise, the junction of the lower peripheral portion of the sealing section 381 and the outer peripheral portion of the diaphragm section 3&2 is wrapped around the lower rim guard 34-6 and is aflixed and sealed thereto by an intervening layer of cement 346'. The extreme upper peripheral edge of the sealing section 331 is arranged in contact with the inner surface of the sealing shoe 340 and suitably secured in place by the plurality of circumferentially spaced-apart clamping fixtures 390, as previously explained.

In this form of the sealing mechanism 331 the sealing element is of composite construction, including the flexible backing member 34%, the intermediate cushioning layer 348 and the outer sealing layer 381; and in the arrangement, the abutting surfaces of the backing member 340 and the intermediate cushioning layer 343 may be secured together, as by cementing, if desired, and likewise, the abutting surfaces of the outer sealing layer 331 and the intermediate cushioning layer 348 may be secured together, as by cementing, if desired. Ordinarily, the cementing in place of the intermediate cushioning layer 343 between the outer sealing layer 381 and the flexible backing layer 34-9 is not required; however, the cementing mentioned does prevent relative movements between the three layers 34%, 348 and 381 incident to the vertical movements of the floating roof 2! with respect to the tank side wall 12 and is thus useful to minimize these relative movements mentioned.

In this form of the sealing mechanism 339, the materials of construction of the sealing shoe 340 and of the element 38% may correspond to .those previously described in conjunction with the sealing shoe 410 and the element St). The general mode of operation of the sealing mechanism 33d is the same as that of the sealing mechanism 39, as previously described, and it is not reiterated in the interest of brevity.

In view of the foregoing, it is apparent that there has been provided in a tank tor storing liquids, such as petroleum products, including a substantially cylindrical upstanding side wall, and a floating roof arranged in the tank and including upstanding substantially cylindrical wall structure spaced radially inwardly from the tank side wall and defining an upstanding substantially annular space therebetween, improved sealing mechanism arranged entirely within the annular space mentioned and comprising a composite annular sealing shoe provided with an outer sealing sheet disposed in firm sliding sealed engagement with the adjacent inner surface of the tank side wall, and a flexible diaphragm sealing the annular space between the cylindrical wall structure and the annular sealing shoe, wherein the outer sealing sheet of the composite sealing shoe and the diaphragm are formed integrally and of a continuous run of flexible sheet material that is highly impervious to the constituents of petroleum products. Moreover, the composite sealing shoe mentioned comprises in addition to the outer sealing sheet, an intermediate resilient cushioning layer and a flexible or limber backing member; whereby the backing member urges through the resilient cushioning layer the outer sealing sheet into firm sliding sealed engagement with the inner surface of the tank side wall. Further, the backing sheet of the composite shoe mentioned is urged radially outwardly from the adjacent upstanding substantially cylindrical wall structure of the floating roof by a pusher device of improved construction and arrangement and consisting essentially of a resilient block of cellular material. The arrangement of the composite sealing shoe as described above is very advantageous, by virtue of the fact that the same may be firmly pressed into sliding sealed engagement with the inner surface of the tank side wall, notwithstanding substantial irregularities therein due to rough joints, lack of proper curvature of the tank side wall, dents and other discontinuities in the interior surface of the tank side wall. Furthermore, the desired sliding sealed engagement may be obtained between the composite shoe and the inner surface of the tank side wall without undue pressure therebetween, with the result that the sliding shoe obtains the desired seal to the inner surface of the tank side wall without scraping or damaging the paint or other protective coating that may be applied thereto. Furthermore, the arrangement wherein the outer sealing sheet of the composite shoe and the diaphragm mentioned are formed integrally with each other and of a continuous run of flexible sheet material is very advantageous as the arrangement substantially minimizes loss by evaporation of the volatile constituents of the liquid petroleum products stored in the tank, thereby both preventing the loss of these valuable products and minimizing the fire hazard incident to the storage of such petroleum products. Finally, the sealing mechanism is of economical construction and arrangement that may be largely prefabricated in a shop and requiring only a minimum number of simple final fabricating steps in the field in the production of the finished sealing mechanism between the floating roof and the tank side wall.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modification-s as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a tank for storing liquids, such as petroleum products, including an upstanding substantially cylindrical side wall, and a floating roof arranged in said tank and including upstanding substantially cylindrical wall structure spaced radially inwardly from said tank side wall and defining a substantially annular space therebetween; sealing mechanism for said annular space comprising an upstanding substantially annular radially yieldable backing member arranged in said annular space and surrounding said Wall structure and located radially outwardly therefrom and disposed closely adjacent to said tank side Wall, the top of said backing member extending upwardly well above the level of the liquid stored in said tank and the bottom of said backing member extending downwardly well below the level of the liquid stored in said tank, a substantially annular element arranged in said annular space and formed of flexible non-metallic sheet material that is highly resistant to the constituents of petroleum products, said element including an outer wear-resistant sealing section and an inner gas-impervious diaphragm section, said sealing section being disposed between said tank side wall and said backing member and said diaphragm section extending between said wall structure and the bottom of said backing member, means carried by said floating roof for supporting said backing member for vertical movements with said floating roof and with respect to said tank side wall and for urging said backing member radially outwardly to press said sealing section into firm sliding sealed engagement with said tank side wall and for accommodating limited sidewise movements of said wall structure with respect to said backing member, the upper peripheral portion of said sealing section being attached to an annular portion of said backing member disposed above the level of the liquid stored in said tank so that said sealing section is pulled upwardly by said backing member incident to upward movement thereof and the lower peripheral portion of said sealing section being attached to an annular portion of said backing member disposed below the level of the liquid stored in said tank so that said sealing section is pulled downwardly by said backing member incident to downward movement thereof, the intermediate portion of said sealing section disposed between the upper and lower peripheral portions thereof being free of attachments to the adjacent engaging portion of said backing member to accommodate vertical adjustments therebetween incident to vertical movements of said backing member so as to preserve the firm sliding sealed engagement between said tank side wall and said backing member notwithstanding the vertical movements of said backing member with respect thereto, the lower peripheral portion of said sealing section joining the outer peripheral portion of said diaphragm section adjacent to the bottom of said backing member and below the level of the liquid stored in said tank and submerged therein, and means for sealing the inner peripheral portion of said diaphragm section to an annular portion of said wall structure disposed above the level of the liquid stored in said tank.

2. The sealing mechanism set forth in claim 1, wherein the material of said element is formed essentially of copolymers of butadiene and acrylonitrile modified with polyvinyl chloride resin.

3. The sealing mechanism set forth in claim 1, wherein said backing member is formed essentially of sheet steel.

4. The sealing mechanism set forth in claim 1, wherein said backing member is formed of sheet material consisting essentially of glass fiber reenforced polyester resin.

5. The sealing mechanism set forth in claim 1, and further comprising means for venting to the atmosphere the upper part of the lower portion of said annular space disposed below said diaphragm section.

6. The sealing mechanism set forth in claim 1, and further comprising an annular layer of cushioning material arranged between said backing member and said sealing section for distributing the outward radial pressure of said backing member upon said sealing section.

7. In a tank for storing liquids, such as petroleum products, including an upstanding substantially cylindrical side wall, and a floating roof arranged in said tank and including upstanding substantially cylindrical wall structure spaced radially inwardly from said tank side wall and defining a substantially annular space therebetween; sealin mechanism for said annular space comprising an upstanding substantially annular radially yieldable backing member arranged in said annular space and surrounding said wall structure and located radially outwardly therefrom and disposed closely adjacent to said tank side wall, the top of said backing member extending upwardly well above the level of the liquid stored in said tank and the bottom of said backing member extending downwardly well below the level of the liquid stored in said tank, a substantially annular element arranged in said annular space and formed of flexible non-metallic sheet material that is highly resistant to the constituents of petroleum products, said element including an outer wear-resistant sealing section and an inner gas-impervious diaphragm section, said sealing section being disposed between said tank side wall and said backing member and said diaphragm section extending between said wall structure and the bottom of said backing member, means carried by said floating roof for supporting said backing member for vertical movements with said floating roof and with respect to said tank side wall and for urging said backing member radially outwardly to press said sealing section into firm sliding sealed engagement with said tank side wall and for accommodating limited sidewise movements of said wall structure with respect to said backing member the upper peripheral portion of said sealing section being attached to an annular portion of said backing member disposed above the level of the liquid stored in said tank so that said ealing section is pulled upwardly by said backing member incident to upward movement thereof and the lower peripheral portion or" said sealing section being attached to an annular portion of said backing member disposed below the level of the liquid stored in said tank so that said sealing section is pulled downwardly by said backing member incident to downward movement thereof, the intermediate portion of said sealing section disposed between the upper and lower peripheral portions thereof being free of attachments to the adjacent engaging portion of said backing member to accommodate vertical adjustments therebetween incident to vertical movements of said backing member so as to preserve the firm sliding sealed engagement between said tank side wall and said backing member notwithstanding the vertical movements of said backing member with respect thereto, the lower peripheral portion of said sealing section joining the outer peripheral portion of said diaphragm section adjacent to the bottom of said backing member and below the level of the liquid stored in said tank and submerged therein, said diaphragm section being loosely draped between the inner and outer peripheral portion thereof and including inner and outer and intermediate parts, the intermediate part of said diaphragm section lying along the upper surface of the liquid stored in the said tank, the inner part of said diaphragm section extending upwardly from the intermediate part thereof to the inner peripheral portion thereof and lying along the lower outer surface of said wall structure, the outer part of said diaphragm section extending downwardly from the intermediate part thereof to the outer peripheral portion thereof and lying along the lower inner surface of said backing member.

8. The sealing mechanism set forth in claim 7, wherein the loose drape of said diaphragm section between the inner and outer peripheral portions thereof causes the material thereof to feed into and out of the intermediate part thereof in response to variation of the draft of said floating roof, whereby an increase in the draft of said floating roof is accompanied by a payout of diaphragm material from the inner part into the intermediate part and thence into the outer part of said diaphragm section while a decrease in the draft of said floating roof is accompanied by a payout of diaphragm material from the outer part into the intermediate part and thence into the inner part of said diaphragm section.

9. The sealing mechanism set forth in claim 7, wherein the total radial width of the diaphragm material included in the intermediate part of said diaphragm section is substantially greater than the normal radial width of the annular space between the outer surface of said wall structure and the inner surface of said backing member so that the intermediate part of said diaphragm section normally includes substantial wrinkles.

10. In a tank for storing liquids, such as petroleum products, including an upstanding substantially cylindrical side wall, and a floating roof arranged in said tank and including upstanding substantially cylindrical wall structure spaced radially inwardly from said tank side wall and defining a substantially annular space therebetween; sealing mechanism for said annular space comprising an upstanding substantially annular radially yieldable backing member arranged in said annular space and surrounding said wall structure and located radially outwardly therefrom and disposed closely adjacent to said tank side wall, the top of said backing member extending upwardly well above the level of the liquid stored in said tank and the bottom of said backing member extending downwardly well below the level of the liquid stored in said tank, a substantially annular element arranged in said annular space and formed of flexible non-metallic sheet material that is highly resistant to the constituents of petroleum products, said element including an outer wear-resistant sealing section and an inner gas-impervious diaphragm section, said sealing section being disposed between said tank side Wall and said backing member and said diaphragm section extending between said wall structure and the bottom of said backing member, means carried by said floating roof for supporting said backing member for vertical movements with said floating roof and with respect to said tank side wall and for urging said backing member radially outwardly to press said sealing section into firm sliding sealed engagement with said tank side wall and for accommodating limited sidewise movements of said wall structure with respect to said backing member, means including a plurality of circumierentially spaced-apart first devices carried by the top of said backing member for attaching the upper peripheral portion of said sealing section to the top of said backing member so that said sealing section is pulled upwardly by said backin member incident to upward movement thereof, means including a plurality of circumferentially spacedapart second devices carried by the bottom of said backing member for attaching the lower peripheral portion or" said sealing section to the bottom of said backing member so that said sealing section is pulled downwardly by said backing member incident to downward movement thereof, the intermediate portion of said sealing section disposed between the upper and lower peripheral portions thereof being free of attachments to the adjacent engaging portion of said backing member to accommodate vertical adjustments therebetween incident to ertical movements of said backing member so as to preserve the firm sliding sealed engagement between said tank side wall and said backing member notwithstanding the vertical movements of said backing member with respect thereto, the lower peripheral portion of said sealing section joining the outer peripheral portion of said diaphragm section adjacent to the bottom of said backing member and below the level of the liquid stored in said tank and submerged therein, and means for sealing the inner peripheral portion of said diaphragm section to an annular portion of said wall structure disposed above the level of the liquid stored in said tank.

11, In a tank for storing liquids, such as petroleum products, including an upstanding substantially cylindrical side wall, and a floating roof arranged in said tank and including upstanding substantially cylindrical wall structure spaced radially inwardly from said tank side wall and defining a substantially annular space therebetween; sealing mechanism for said annular space comprising an upstanding substantially annular radially yieldable backing member arranged in said annular space and surrounding said wall structure and located radially outwardly therefrom and disposed closely adjacent to said tank side Wall, the top of said backing member extending upwardly well above the level of the liquid stored in said tank and the bottom of said backing member extending downwardly well below the level of the liquid stored in said tank, a substantially annular element arranged in said annular space and formed of flexible non-metallic sheet material that is highly resistant to the constituents of petroleum products, said element including an outer wear-resistant sealing section and an inner gas-impervious diaphragm section, said sealing section being disposed between said tank side wall and said backing member and said diaphragm section extending between said wall structure and the bottom of said backing member, means carried by said floating roof for supporting said backing member for vertical movements with said floating root and with respect to said tank side Wall and for urging said backing member radially outwardly to press said sealing section into firm sliding sealed engagement with said tank side Wall and for accommodating limited sidewise movements of said wall structure with respect to said backing member, a first resilient ring secured to the top of said backing member, a second resilient ring secured to the bottom of said backing member, the upper peripheral portion of said sealing section being secured and sealed to said first ring so that said sealing section is pulled upwardly by said backing member incident to upward movement thereof and the lower peripheral portion of said sealing section being secured and scaled to said second ring so that said sealing section is pulled downwardly by said backing member incident to downward movement thereof, the intermediate portion of said sealing section disposed between the upper and lower peripheral portions thereof being free of attachments to the adjacent engaging portion of said backing member to accommodate vertical adjustments therebetween incident to vertical movements of said backing member so as to preserve the firm sliding sealed engagement between said tank side wall and said backing member notwithstanding the vertical movements of said backing member with respect thereto, me lower peripheral portion of said sealing section joining the outer peripheral portion of said diaphragm section at said second ring and below the level of the liquid stored in said tank and submerged therein, and means for sealing the inner peripheral portion of said diaphragm section to an annular portion of said wall structure disposed above the level 01" the liquid stored in said tank.

12. In a tank for storing liquids, such as petroleum products, including an upstanding substantially cylindrical side wall, and a floating roof arranged in said tank and including upstanding substantially cylindrical wall structure spaced radially inwardly from said tank side Wall and defining a substantially annular space therebetween; sealing mechanism for said annular space comprising an upstanding substantially annular sealing element arranged in said annular space and surrounding said wall structure and located radially outwardly therefrom and closely adjacent to said tank side wall, the top of said sealing element extending upwardly well above the level of the liquid stored in said tank and the bottom of said sealing element extending downwardly well below the level of the liquid stored in said tank and submerged therein, said sealing element being of composite construction including an inner radially yieldable backing sheet and an intermediate cushioning layer and an outer resilient sealing layer, said intermediate cushioning layer covering the outer surface of said backing sheet, said sealing layer covering the outer surface of said intermediate cushioning layer, the outer surface of said sealing layer being disposed in direct engagement with the inner surface of said tank side wall, said sealing layer being formed of flexible non-metallic sheet material that is highly resistant to the constituents of petroleum products and that is also wear-resistant, means carried by said floating roof for supporting said sealing element for vertical movements with said floating roof and with respect to said tank side wall and for urging said backing sheet radially outwardly to press through said cushioning layer said sealing layer into firm sliding sealed engagement with said tank side wall and for accommodating limited sidewise movements of said wall structure with respect to said backing sheet, the upper peripheral portion of said sealing layer being attached to an annular portion of said backing s -eet disposed above the level of the liquid stored in said tank so that said sealing layer is pulled upwardly by said backing sheet incident to upward movement thereof and the lower peripheral portion of said sealing layer being attached to an annular portion of said backing sheet disposed below the level of the liquid stored in said tank so that said sealing layer is pulled downwardly by said backing sheet incident to downward movement thereof, the intermediate portion of said sealing section disposed between the upper and lower peripheral portions thereof being free of attachments to the adjacent engaging portion of said backing member to accommodate vertical adjustments therebetween incident to vertical movements or" said backing member so as to preserve the firm sliding sealed engagement between said tank side Wall and said backing member notwithstanding the vertical movements of said backing member with respect thereto, and a sub: stantially annular diaphragm formed of flexible material that is highly impervious to the constituents of petroleum products arranged in said annular space and extending between said wall structure and said sealing element, the inner peripheral portion of said diaphragm being sealed 17 to an annular portion of said wall structure and the outer peripheral portion of said diaphragm being sealed to an annular portion of said sealing element.

13. The sealing mechanism set forth in claim 12, wherein said sealing layer is formed essentially of copolymers of butadiene and acrylonitrile modified with polyvinyl chloride resin.

14. The sealing mechanism set forth in claim 12, wherein said intermediate cushioning layer is formed essentially of synthetic organic resin of cellular structure.

15. The sealing mechanism set forth in claim 12, wherein said intermediate cushioning layer is formed essentially of foamed polyurethane.

16. In a tank for storing liquids, such as petroleum products, including an upstanding substantially cylindrical side wall, and a floating roof arranged in said tank and including upstanding substantially cylindrical wall structure spaced radially inwardly from said tank side Wall and defining a substantially annular space therebetween; sealing mechanism for said annular space comprising an upstanding substantially annular radially yieldable backing member arranged in said annular space and surrounding said wall structure and located radially outwardly therefrom and disposed closely adjacent to said tank side wall, the top of said backing member extending upwardly well above the level of the liquid stored in said tank and the bottom of said backing member extending downwardly well below the level of the liquid stored in said tank, a substantially annular element arranged in said annular space and formed of flexible non-metallic sheet material that is highly resistant to the constituents of petroleum products, said element including an outer wearresistant sealing section and an inner gas-impervious diaphragm section, said sealing section being disposed between said tank side wall and said backing member and said diaphragm section extending between said wall structure and the bottom of said backing member, means carried by said floating roof for supporting said backing member for vertical movements with said floating roof and with respect to said tank side wall and for urging said backing member radially outwardly to press said sealing section into firm sliding sealed engagement with said tank side wall and for accommodating limited sidewise movements of said wall structure with respect to said backing member, the upper peripheral portion of said sealing section being attached to an annular portion of said backing member disposed above the level of the liquid stored in said tank so that said sealing section is pulled upwardly by said backing member incident to upward movement thereof and the lower peripheral portion of said sealing section being attached to an annular portion of said backing member disposed below the level of the liquid stored in said tank so that said sealing section is pulled downwardly by said backing member incident to downward movement thereof, the intermediate portion of said sealing section disposed between the upper and lower peripheral portions thereof being free of attachments to the adjacent engaging portion of said backing member to accommodate vertical adjustments therebetween incident to vertical movements of said backing member so as to preserve the firm sliding sealed engagement between said tank side wall and said backing member notwithstanding the vertical movements of said backing member with respect thereto, the lower peripheral portion of said sealing section joining the outer peripheral portion of said diaphragm section adjacent to the bottom of said backing member and below the level of the liquid stored in said tank and submerged therein, the top of said backing member also extending upwardly Well above the top of said wall structure, and a substantially annular weather hood for protecting said annular space against the elements of weather, the outer peripheral portion of said weather hood being secured to the top of said backing member and projecting downwardly and radially inwardly therefrom over the top outer peripheral portion of said wall structure so as to shed Water onto said floating roof.

References ited in the file of this patent UNITED STATES PATENTS 1,463,268 Huif July 31, 1923 2,426,755 Ulm Sept. 2, 1947 2,523,292 Goldsby et al Sept. 26, 1950 2,754,026 Wiggins July 10, 1956 2,981,436 Fino et al Apr. 25, 1961 2,987,215 Joor June 6, 1961 3,059,805 Joor Oct. 23, 1962 FOREIGN PATENTS 830,489 Great Britain Mar. 16, 1960 1,196,283 France Nov. 23, 1959 

1. IN A TANK FOR STORING LIQUIDS, SUCH AS PETROLEUM PRODUCTS, INCLUDING AN UPSTANDING SUBSTANTIALLY CYLINDRICAL SIDE WALL, AND A FLOATING ROOF ARRANGED IN SAID TANK AND INCLUDING UPSTANDING SUBSTANTIALLY CYLINDRICAL WALL STRUCTURE SPACED READIALLY INWARDLY FROM SID TANK SIDE WALL AND DEFINING A SUBSTANTIALLY ANNULAR SPACE THEREBETWEEN; SEALING MECHANISM FOR SAID ANNULAR SPACE COMPRISING AN UPSTANDING SUBSTANITALLY ANNULAR RADIALLY YIELDABLE BACKING MEMBER ARRANGED IN SAID ANNULAR SPACE AND SURROUND SAID WALL STRUCTURE AND LOCATED RADIALLY OUTWARDLY THEREFROM AND DISPOSED CLOSELY ADJACENT TO SAID TANK SIDE WALL, THE TOP OF SAID BACKING MEMBER EXTENDING UPWARDLY WELL ABOVE THE LEVEL OF THE LIQUID STORED IN SAID TANK AND THE BOTTOM OF SAID BACKING MEMBER EXTENDING DOWNWARDLY WELL BELOW THE LEVEL OF THE LIQUID STORED IN SAID TANK, A SUBSTANTIALLY ANNULAR ELEMENT ARRANGED IN SAND ANNULAR SPACE AND FORMED OF FLEXIBLE NON-METALLIC SHEET MATERIAL THAT IS HIGHLY RESISTANT TO THE CONSTITUENTS OF PETROLEUM PRODUCTS, SAID ELEMENT INCLUDING AN OUTER WEAR-RESISTANT SEALING SECTION AND AN INNER GAS-IMPERVIOUS DIAPHRAGM SECTION, SAID SEALING SECTION BEING DISPOSED BETWEEN SAID TANK SIDE WALL AND SAID BACKING MEMBER AND SAID DIAPHRAGM SECTION EXTENDING BETWEEN SAID WALL STRUCTURE AND THE BOTTOM OF SAID BACKING MEMBER, MEANS CARRIED BY SAID FLOATING ROOF FOR SUPPORTING SAID BACKING MEMBER FOR VERTICAL MOVEMENTS ITH SAID FLOATING ROOF AND WITH RESPECT TO SAID TANK SIDE WALL AND FOR URGING SAID BACKING MEMBER RADIALLY OUTWARDLY TO PRESS SAID SEALING SECTION INTO FIRM SLIDING SEALED ENGAGEMENT WITH SAID TANK SIDE WALL AND FOR ACCOMODATING LIMITED SIDEWISE MOVEMENTS OF SAID WALL STRUCTURE WITH RESPECT TO SAID BACKING MEMBER, THE UPPER PERIPHERAL PORTION OF SAID SEALING SECTION BEING ATTACHED TO AN ANNULAR PORTION OF SAID BACKING MEMBER DISPOED ABOVE THE LEVEL OF THE LIQUID STORED IN SAID TANK SO THAT SAID SEALING SECTION IS PULLED UPWARDLY BY SAID BACKING MEMBER INDICIDENT TO UPWARD MOVEMENT THEREOF AND THE LOWER PERIPHERAL PORTION OF SAID SEALING SECTION BEING ATTACHED TO AN ANNULAR PORTION OF SAID BACKING MEMBER DISPOSED BELOW THE LEVEL OF THE LIQUID STORED IN SAID TANK SO THAT SAID SELAING SECTION IS PULLED DOWNWARDLY BY SAID BACKING MEMBER INCIDENT TO DOWNWARD MOVMENT THEREOF, THE INTERMEDIATE PORTION OF SAID SEALING SECTION DISPOSED BETWEEN THE UPPER AND LOWER PERIPHERAL PORTIONS THEREOF BEING FREE OF ATTACHMENTS TO THE ADJACENT ENGAGING PORTION OF SAID BACKING MEMBER TO ACCOMODATE VERTICAL ADJUSTMENTS THEREBETWEEN INCIDNET TO VERTICAL MOVEMENTS OF SAID BAKCING MEMBER SO AS TO PRESERVE THE FIRM SLIDING SEALED ENGAGEMENT BETWEEN SAID TANK SIDE WALL AND SAID BACKING MEMBER NOTWITHSTANDING THE VERTICAL MOVEMENTS OF SAID BACKING MEMBER WITH RESPECT THERETO, THE LOWER PERIPHERAL PORTION OF SAID SEALING SECTION JOINING THE OUTER PERIPHERAL PORTIONS OF SAID DIAPHRAGM SECTION ADJACENT TO THE BOTTOM OF SAID BACKING MEMBER AND BELOW THE LEVEL OF THE LIQUID STORED IN SAID TANK AND SUBMERGED THEREIN, AND MEANS FOR SEALING THE INNER PERIPHERAL PORTION OF SAID DIAPHRAGM SECTION TO AN ANNULAR PORTION OF SAID WALL STRUCTURE DISPOED ABOVE THE LEVEL OF THE LIQUID STORED IN SAID TANK. 